Introduction of Pressing Fastness Test | Color Fastness to Pressing

Color Fastness to Pressing:
Pressing fastness test of dyed and printed textile products is performed to determine of resistance of textiles to ironing and to processing on cylinders. Different tests are performed according to when the textile is dry, when it is wet, and when it is damp. 

Purpose and Scope:
This method is used for determining the resistance of the colour of textile of all kinds and in all forms to ironing and processing on hot cylinders. Tests are given for hot pressing when the textiles are wet, when it is damp, and when it is dry.

Apparatus and Reagent  

• Hand iron of proper weight to give a pressure of approximately 30g/sq.cm at the temperature indicated in the following ;

1. Cotton & Linen 190-200C˚
2. Wool, Silk & Viscose 140-160C˚
3. Cellulose acetate & Polyamide 115-120C˚

• White bleached cotton cloth weighting approximately 125g/sq.meter. Five pieces not less than 14×4 cm are required. 
• Gray scale by assessing change in colour and staining.(ISO scale)  
• The size of the specimen is 10×4cm

Working Procedure
Specimen preparation
Specimen of materials, which has been subjected to any heat or drying treatment, must be allowed to condition at 65% RH, temp. 20±2C˚, before they tested.

Dry Pressing
Place the specimen on the piece of dry cotton cloth on a smooth horizontal surface. Place the iron on the specimen and leave it for 15 Sec.

Damp Pressing: 

The adjacent fabric in dimensions of 100 mm x 40 mm is immersed into the water and, squeezed as 100% pick up. Dry specimen is placed onto the undyed cotton fabric on the filler and, the wet adjacent fabric is placed onto them. The top layer of the device is pulled down and, dry specimen is pressed for 15 seconds at the determined temperature. The change in color of the specimen is evaluated in two different ways according to grey scale.

a) Soon after the end of the test
b) After conditioning for 4 hours under standard atmospheric circumstances.
The staining to undyed fabrics is evaluated by grey scale.

Wet Pressing
Soak the specimen and cotton cloth in distilled water and squeeze or extract them to contain their own weight of water. Place the wet specimen on a piece of the dry cotton cloth and place the wet cotton cloth on the specimen, press by moving the iron to and fro over the wet cloth (without additional pressure) for 15 sec.

Assessment
Assess the change in colour of the specimen with appropriate grey scale.

Standard
Dry Pressing 4
Wet Pressing 3-4 

Introduction of Perspiration Test | Color Fastness to Perspiration

The color fastness to perspiration (acid and alkaline) shall be at least level 3-4 (color change and staining). This criterion does not apply to white products, to products that are neither dyed nor printed, to furniture fabrics, curtains or similar textiles intended for interior decoration. A level of 3 is nevertheless allowed when fabrics are both light colored (standard depth

Color Fastness to Perspiration
The garments a\which come into contact with the body where perspiration is heavy may suffer serious local discoloration. This test is intended to determine the resistance of color of dyed textile to the action of acidic and alkaline perspiration. Before knowing about the Color Fastness to perspiration you must have to know about Color Fastness to Wash and Color Fastness to Rubbing.

Perspirometer

Well, in today’s class you will know about the perspiration matters which affects on Color fastness.

Purpose and Scope
This method is used to determine the resistance of the colour of textile of all kinds and in all forms to perspiration.

Equipment For Fastness Measurement

1. Perspiration tester
2. Oven, Maintained at 37+-2 Degree centigrade
3. Multifiber test fabric
4. Grey scale
5. Color matching chamber
6. Acidic and Alkaline solution
7. Glass or Acrylic plat
8. Weight.

Reagent for Perspiration Test

1. Solution freshly prepared, containing 0.5g 1-histidine mono-hydrochloride mono-hydrate, 5g sodium chloride, and 2.5g disodium hydrogen ortho phosphate per litre brought to PH 8.0 with 0.1N sodium hydroxide.
2. Solution freshly prepared, containing 0.5g 1-histidine mono-hydrochloride mono-hydrate, 5g sodium chloride, and 2.2g sodium dihydrogen ortho phosphate per litre brought to PH 5.5 with 0.1N sodium hydroxide.
3. Two undyed cloths for each specimen each 6×6cm of the same kind of fibre as the sample. Place the specimen between the two pieces of white cloth and sew along one side to form a composite sample.

Working Procedure :
Thoroughly wet one composite sample in a solution of PH8.0 at the liquor ratio of 20:1 and allow it to remain in this solution at room temperature for 30min. pour off the solution and place the composite sample between two glasses plates measuring about 7.5×6.5cm under a force of about 4.5kg.

1. Treat the other sample in the same way but with the solution at PH 5.5.
2. Place the apparatus containing the samples in the oven for 4 hour at 37±2C˚
3. Separate the sample from the white cloth and dry them apart in air at the temperature not exceeding 60C˚
4. Assess the change in colour of the specimen and the staining of the white cloth with the greigh scale.

What is Fastness? | Color Fastness Scales | Colour Change Grey Scales |Degree of Staining Grey Scales

Fastness:

Fastness is the resistance of a textile material to specific chemical agencies. Poor colour fastness in textile products is a major source of customer complaint. The fastness of a colour can vary with the type of dye, the particular shade used, the depth of shade and how well the dyeing process has been carried out. Dyes can also behave differently when in contact with different agents, for instance dyes which may be fast to dry-cleaning may not be fast to washing in water. It is therefore important to test any dyed or printed product for the fastness of the colours that have been used in its decoration.

There are a number of agencies that the coloured item may encounter during its lifetime which can cause the colour either to fade or to bleed onto an adjacent uncoloured or light coloured item. These factors vary with the end use for which the product is intended. For instance carpets and upholstery are cleaned in a different way from bed linen and clothing and therefore come into contact with different materials. The agencies that affect coloured materials include light, washing, dry-cleaning, water, perspiration and ironing. There are a large number of colour fastness tests in existence which deal with these agencies and a full list will be found in the British Standard. A further group of tests is connected to processes in manufacturing that the coloured material may undergo after dyeing but before completion of the fabric, processes such as decatising or milling. Despite the fact that the list of colour fastness tests is very long, most of them are conducted along similar lines so that the main differences among the tests are in the agents to which the material is exposed.

Colour fastness is usually assessed separately with respect to:
1 changes in the colour of the specimen being tested, that is colour fading;
2 staining of undyed material which is in contact with the specimen during the test, that is bleeding of colour.

In order to give a more objective result a numerical assessment of each of these effects is made by comparing the changes with two sets of standard grey scales, one for colour change and the other for staining.

1. Colour Change Grey Scales

These scales consist of five pairs of grey coloured material numbered from 1 to 5. Number 5 has two identical greys, number 1 grey scale shows the greatest contrast, and numbers 2, 3 and 4 have intermediate contrasts. After appropriate treatment the specimen is compared with the original untreated material and any loss in colour is graded with reference to the grey scale. When there is no change in the colour of a test specimen it would be classified as ‘5’; if there is a change it is then classified with the number of the scale that shows the same contrast as that between the treated and untreated specimens. 

 

Fig: Gray Scale

2 .Degree of Staining Grey Scales

A different set of grey scales is used for measuring staining. Fastness rating 5 is shown by two identical white samples (that is no staining) and rating 1 shows a white and a grey sample. The other numbers show geometrical steps of contrast between white and a series of greys. A piece of untreated, unstained, undyed cloth is compared with the treated sample that has been in contact with the test specimen during the staining test and a numerical assessment of staining is given. A rating of 5 means that there is no difference between the treated and untreated material. If the result is in between any two of the contrasts on the scale, a rating of, for example, 3-4 is given. Sets of grey scales, examples of which are shown in Fig: can be supplied by the British Standards Institution.

Rubbing Fastness Test | Color Fastness To Rubbing

A fastness is a place, such as a castle, which is considered safe because it is difficult to reach or easy to defend against attack. This test is designed to determine the degree of color which may be transferred from the surface of a colored fabric to a specify test cloth for rubbing (which could be dry and Wet).

There are two test methods for rubbing fastness.

1.ISO-105-X12 

2.AATCC-08 

In ISO-105-X12 the wet pickup of the rubbing cloth is 100% .While in AATCC-08 the wet Pickup of the rubbing cloth is 65%.We check rubbing by Dry and Wet methods. In wet rubbing we wet the rubbing cloth according to test method and give rating by comparing the Staining with the gray scale.

Similarly for dry rubbing we check the rubbing with dry rubbing cloth and compare the staining With gray scale for ratings.Color Fastness to rubbing is a main test which is always required for every colored fabric either it is Printed or dyed.

If the color fastness to rubbing is good then its other properties like Washing fastness and durability etc improves automatically because the rubbing is a method to check the fixation of the color on the fabric. So if the fixation is good its washing properties will be good.

Rubbing Fastness depends on: 

• Nature of the Color 
• Depth of the Shade 

Construction of the FabricNature of the color Each color either it is pigment ,Reactive ,Disperse or direct has its own fastness properties to rubbing. There are some colors like black, Red ,Burgundy ,Navy blue which have poor Color fastness properties because of their chemical structure.

Like Black color is a carbon base color and the particle size of carbon is large than the other colors that’s why its rubbing properties are poor. Similarly red and blue are in the same case. So to improve the color fastness we add more binder to improve the fastness properties of these colors. It doesn’t mean that we can not achieve the best results with these colors. The required results can achieve but production cost will be increase. On the other hand the construction of the fabric also effects the fastness properties.

If the rubbing fastness on 100.80/40.40 is 3 on the gray scale it will be 2-3 on 52.52/22.22 with the same printing parameters. So always keep in mind these effects during finalize the required parameters with your customer .

Always Check 

• Quality construction 
• Color 
• Depth of the Color 
• End Use of the product

Results which we can achieve in Normal Conditions are

	Dark Shade	Medium shades	Light Shades
Dry	3-4	4	4-5
Wet	2-2.5	3	3.5-4